How do I know I’m doing Tightercise right?

If your muscle gives out after clenching very hard for 2-5 seconds, you’re doing Tightercise right. If not, you’re not clenching hard enough. Everyone, regardless of fitness level, can reach this “burnout” in 2-5 seconds. The important thing is to go for intensity over sustainability: you want to clench your muscles as hard as you possibly can. It’s difficult to achieve this with usual gym exercises because it’s easy for the resistance to be either too low or too high to fully shorten and clench your muscle. But since you’re just using your own fresh muscles in Tightercise, you face practically no risk of injury. So, you might be able to safely engage your muscles harder and get better results than you ever have before.